If you go to https://test.wikipedia.org/w/index.php?title=User:Huji/diff&diff=387036&oldid=387035 you not only see which line changed, but you also see specifically which part of the lines was modified (in the HTML, it is highlighted using <del> and <ins> tags).

However, the information AbuseFilter shows for that diff (accessible at https://test.wikipedia.org/wiki/Special:AbuseFilter/examine/426401) is only at the line level. I can think of many cases when knowing the exact portions that were changed is useful for a filter.

I think a good way to do that is to have two new variables: edit_diff_added and edit_diff_removed. They should each be an array of only the added/removed fragments (so for the example above, we would have edit_diff_added = ['some'] and edit_diff_removed = ['a'])

A less optimal, but still workable solution is to literally expose the HTML of the diff as a variable (so one could look for a pattern like <ins>some</ins> in it).